1. Field of the Invention
The present invention relates to a discharge device and image forming apparatuses, such as copying machines and printers, using a discharge device.
2. Description of the Related Art
FIG. 5 is a cross-sectional view of a copying machine of the electrophotographic type.
As FIG. 5 shows, an electrostatic image is formed on the surface of a photosensitive drum 104 through the use of an optical unit 103, an electrifying device 203 and other components and, subsequently, a toner serving as a developer is attached to the electrostatic image by means of a developing device 201 so that the electrostatic image develops into a visible image. Additionally, this visible image is transferred through a transferring device 111 onto a transfer material conveyed by feeding means 105 to 110 and the transfer material with the visible image on it is separated from the photosensitive drum 104 by a separating device 112 and subsequently conveyed by a conveying means 113 to a fixing device 114 where it is heated and pressurized to fix the visible image. The transfer material on which the visible image has been fixed is ejected outside of the copying machine through an ejecting device 116.
Meanwhile, if a paper jam occurs during an image forming operation, the removal of the jammed paper becomes necessary. In addition, a need for periodical apparatus-interior maintenance exists. Therefore, for easy jam elimination and maintenance, there has been proposed a construction in which a section indicated by a broken line in FIG. 5 is made as a single fixing/conveying unit 300 and this fixing/conveying unit 300 is drawable toward the front side of the image forming apparatus along a guide rail (not shown).
In this construction, the fixing/conveying unit 300 includes the transferring device 111 and the separating device 112, which each require a high-voltage contact for its power supply. For the unit configuration, the high-voltage contact is disposed in the vicinity of either the transferring device 111 or the separating device 112 and at a position where the connection with the main body is facilitated. Taking this into consideration, the high-voltage contact is positioned on the rear surface of the transferring device 111 and the separating device 112, that is, on the rear surface of the fixing/conveying unit 300.
Furthermore, an AC voltage is to be applied to the separating device 112. The electrifying device, thus designed to use an AC voltage, tends to generate radiation noise.
FIG. 6 is an enlarged cross-sectional view showing a high-voltage contact section for the separating device 112 in the image forming apparatus of FIG. 5.
As FIG. 6 shows, the high-voltage contact section for the separating device 112 in the image forming apparatus is composed of a separating device contact portion 51, a separating device block 52, a spring latching plate 55, a main body contact 61, a main body contact block 62, a base plate contact 61 and a main body frame 70.
The high-voltage contact section for the separating device 112 is constructed in a manner that the separating device contact portion 51 is inserted into a cylindrical portion 52a of the separating device block 52 and secured to a spring latch 55. Additionally, an electrifying wire (not shown) is attached through a spring 56 to the spring latch 55 to establish the electrical connection.
On the other hand, in the contact section on the image forming apparatus main body side, the main body contact 61 and the base plate contact 63 are attached to the main body contact block 62, with them being connected electrically to each other. Additionally, the base plate contact 63 is connected to a main body high-voltage base plate (not shown), while the main body contact block 62 is attached to the main body frame 70.
The separating device contact portion 51 is brought into contact with the main body contact 61, the latter made with an elastic material, thereby establishing electrical connection therebetween. A high AC voltage generated from a main body high-voltage base plate (not shown) is supplied to the base plate contact 63, the main body contact 61 and the separating device contact portion 51 so that the electrifying wire (not shown) produces corona discharge, thereby accomplishing separation of a transfer material.
While the separating device 112 conducts the separating operation, a radiation noise may occur at the high-voltage contact section.
If a right-hand area of the main body frame 70 is exterior to the apparatus, the radiation noise tends to leak toward the exterior of the apparatus. For this reason, a shielding mechanism is required to prevent the leakage of the radiation noise.
Accordingly, it is an object of the present invention to provide an image forming apparatus capable of reducing noises to be radiated to the external.
Another object of this invention is to provide a discharge device capable of reducing radiation noise at a high-voltage contact section.
In accordance with these objects, there is provided a discharge device comprising a discharging unit, a supporting member for supporting the discharging unit, and an electrifying device contact portion. A resistor element is placed between the discharging unit and the electrifying device contact portion.
In accordance with another aspect of the invention there is provided an image forming apparatus with an image forming unit having a high-voltage component. An AC base plate communicates power to the high-voltage component of the image forming unit thru a main body contact and an attachable/detachable high-voltage contact section. The high-voltage contact section includes a discharging unit, a supporting member for supporting the discharging unit, an electrifying device contact portion in contact with the main body contact and a resistor element placed between the discharging unit and the electrifying device contact portion.
Other objects of the present invention will become more readily apparent from the following description.